With the rapid growth of wireless telecommunication systems, system providers are challenged to provide quality radio frequency (RF) signals with maximum coverage. In a wireless telecommunications system, a mobile phone needs to be calibrated to provide the power necessary to reach the base station. On the other hand, in order to conserve battery life, the power transmitted should not be more than what is needed. The mobile phone must be able to tune the output power for an optimum connection. Also, the base station and mobile phone must not exceed the maximum allowable power transmitted according to government standards and regulations. Therefore, assuring that the transmitted power does not exceed the allowable limit, which is traced to a known standard, is a primary concern. Thus, accurate power measurements are important for maintaining a high quality connection in modern telecommunication systems.
As with many other types of signals, an RF signal can be made up of a sequence of pulses. In the case of a pulsed RF power signal, the pulses have a leading rising edge and a trailing falling edge. The power envelope of the RF signal is, in some cases, determined by the RF signal's modulation type. In order to measure, for example, the average transmitted power, it is necessary to identify each pulse and to measure particular parameters of each pulse individually. However, in Wireless LAN applications, the pulses may not be of the same width, making their identification and measurement quite difficult. Furthermore, if a pulse is not an exact predetermined fixed distance from a trigger point, it may, again, be difficult to locate, particularly over a relatively long timescale without any pulses. If repetitive pulses are to be measured, then it is almost impossible to do so if they vary in position relative to the trigger point.
In other cases, the pulses within a sequence may have different characteristics from others in the sequence, for example because of the amplifiers used in the generation of the pulses heat up. Measurement of the differences is then necessary in order to make sure that all the pulses remain within the required parameters.
In known circuitry for extracting individual pulses from a sequence of pulses, which may occur irregularly, the whole sequence, or at least a large part thereof, has first been captured into memory and then, subsequently, processed to look for the pulses and perform measurements on them. A fair amount of time can therefore be wasted on processing the non-pulsed information. Furthermore, extracting and delineating the pulses can be algorithmically complex in the presence of strange-shaped or modulated pulses. The main disadvantage of this technique is that the memory will have a finite size. If the pulses are too far apart from each other then they will either be missed or the sampling rate of the Analog to Digital Converter (ADC) used for digitising the analog input signal would need to be reduced in order to sample over a longer period of time. The disadvantage of the latter is that the measurement resolution is reduced. It may, in the worst case, sample at a rate less that the pulse width resulting in only one or even no samples of the desired pulse.
In other known techniques, in order to save on memory, the spaces between pulses are not stored. This allows the pulses themselves to be captured at maximum data rates, but, clearly, they need to be accurately extracted for capture. However, in order to process a pulse, it is necessary to know what the signal was doing before the front edge trigger point and what it does after the back edge trigger point. An example of where this is necessary is in the determination of pulse edge rise and fall time measurement. For two pulses that are very close together, the trailing edge of one pulse may form part of the leading edge of the next pulse. In such cases, the determination of the trailing edge of the first pulse may occur after the leading edge of the next pulse has passed. If this happens, then the second pulse may not be captured properly, or at all, because its existence would not be looked for until after the trailing edge of the previous pulse is detected.